In general, the subject matter relates to pasteurizers for pasteurizing milk from harmful bacteria. The prior art devices generally have heat exchangers where water is used in a countercurrent between the tube or plate heat exchangers to heat up milk passing therethrough. The disadvantage of this is that water heaters can generally be rather expensive, and further, there are issues of cleaning the heat exchangers in the event that scalding or other depository type buildup occurs within the heat exchanger. Heat exchangers are not known for being easy to clean, so an alternative method of heating the milk for pasteurizing purposes is a present need in the marketplace.
The water contained in prior art heat exchange systems is in a close loop circulation which is the sole purpose of having heat transferred to the product. This water is not potable, and the heater is absolutely dedicated to the pasteurizer.
In general, for proper pasteurization, there is an FDA scale that has a valuation for determining the proper amount of time and temperature for pasteurization of milk products. In one form, a lower temperature at a longer period of time will function as a proper pasteurization duration. Alternatively, a higher temperature for a lower period of time will function as well. For example, having the milk product at approximately 145° F. for 30 minutes is considered a proper pasteurization cycle. Alternatively, having the milk at approximately 161° for 15 seconds will also be a sufficient temperature and time combination for proper pasteurization.
As described herein in detail, the disclosure provides a central chamber region, there is a first end having a discharge nozzle from a pump unit where on the opposing longitudinal end there is an intake portion which is in communication with the discharge. The discharge and input ends are adapted to circulate the product rather violently across the lower base surface of the central chamber region. It should be noted that the bottom portion is in direct contact (or direct thermal communication) with an open-flame chamber positioned therebelow. The open-flame chamber is powered by a gaseous, combustible fluid such as liquid propane or natural gas. Heat transfer passes up vertically and is essentially contained in the lateral and lower portions as well as longitudinal forward rearward portions by a fire block which has insulating properties. Therefore, the least path of thermal resistance is upward to the milk chamber where the milk product is contained. By passing the milk product at a fairly high rate of velocity, the milk convection is adapted to have a high rate of heat transfer without having a localized heat transfer to any milk particle which hence causes scalding. However, there is further a thermal couple which is connected to a PLC controller which monitors the temperature of the milk.
Present analysis indicates in various journals that having the high temperature short time (HTST) is more advantageous because there are theories presently circulating indicating that the hemoglobin around certain particles of milk will act as an insulating layer, thereby not allowing heat transfer to the inner particle portions. The present embodiment employs force convection across the heating surface, which should perhaps assist not only in preventing scalding and having a higher temperature heat source, but further prevent any such insulating boundaries within the particles from being formed, or if they are formed, breaking them up.
With regard to additional features of the disclosure, there is a “Clean in Place” (CIP) system. This system is in effect after all the product is removed after a pasteurization cycle. In general, after the unit is emptied, the unit is rinsed out with warm water to clear out all high volume of foam milk solids and so forth.
The pump has the synergistic effect of working as three different functions at three different times during the operation of the unit. Of course, the first and primary unit is circulation of the product during the pasteurization where the high volume flow prevents any scalding or increasingly high localized heat transfer to any portion of the fluid product. Further, the hose in the longitudinally rearward portion can be detached where the pump can function as filling up small container bottles that are adapted to have nipples placed thereon and fed to calves or any other external container for transporting of the pasteurized milk. Further, on the inward portion within the chamber region of the cleaning unit, an additional nozzle can be placed there to disperse cleaning fluid in a desirable pattern to clean out the central chamber area after a pasteurization cycle.
There is further a throttle control with the valve for reducing the rate of flow to the dispersion nozzles for filling external smaller tanks or containers. In one form the pump is adapted to operate at variable forms.
As noted in the figure showing the exposed fire blocks, the flame jet extends in the longitudinally forward direction with the under-portion exposed to allow flames to disperse therefrom. In this orientation the flame jet extends to the forward longitudinal portions for a dispersion of the flame throughout the under-portion of the milk chamber. In the lower portion there is a discharge flute where there is a desirable flow of the combusted gas to the discharge flute which of course is fluted up to a proper external exhaust away from the unit.
Therefore, it should be reiterated that the general theme of the invention is that conventional wisdom is to heat milk with a thermal capacitance intermediate layer between a heat source such as a wire coil, combusted material, or any other conventional heat source, and the actual product which cannot get too hot because of scalding and other associated problems. Therefore, having a heat source which is in direct thermal communication by a thin piece of highly conductive material such as stainless steel is not an intuitive leap. However, by having a strong convection current of the milk passing over this directly heated unit where the convection is at a constant, continuously flowing rate, there is not a localized heat transfer to any one single water molecule or portion of that fluid. Further, present theoretical analysis indicates that a higher temperature is advantageous for purposes of having heat transferred to potential water clumplets within the product that act as a thermal barrier for having heat transfer to the center of those “hemoglobin clumplets”. However, as mentioned previously, present analysis indicates that the circulation has a synergistic effect of breaking up or preventing such clumplets so such heat transfer is provided to all portions of the product. Essentially, there is a lot of stirring going on so that the milk doesn't clump or heat up too much. There is further agitated air in the combustion chamber having a force convection effect down thereunder to have a more uniform heat transfer coming from the under-portion.
It should be reiterated that the lower substantially planar surface of the chamber is not an ideal heat transfer surface area. Normally, if you look at any type of heat transfer unit such as a radiator, there is a plurality of thin-like structures that are adapted to have heat conducted therethrough. In general, the thin structures are made of a highly thermally conductive material, such as metal, and are adapted to draw heat from the heat source to the low temperature area. However, this heat transfer may have adverse effect in this application where the transfer of the heat could have localized hot spots which cause an undesirable scalding and other effects to the milk product.
Therefore, the unit described herein has thermal efficiency in that it utilizes energy by way of the combustible gas and there is a believed to be a lower gradient of heat transfer throughout the X and Y coordinates of the baseplate.
It should be noted that in one form, in the lower portion, there is one heat exchanger that is adapted to be used for cooling the product after it has finished pasteurizing. Essentially, the tube cooler located in the lower portion will cool the milk to a desirable temperature such as to a calf feeding temperature which is typically about 100° F. The tube coolers and the water passing therethrough in the countercurrent flow arrangement comes out warmer, which is either discarded or ran into a trough to give feeding cows warm water for direct consumption.
In one form in the lower lateral portion, there can be a bank array of solenoid valves in fluid communication with hot and cold water sources whereby the PLC controller will control these at various time portions during the run cycle to allow the various functions described above, such as after the milk is pasteurized, the PLC controller allows the product to pass through the lower heat exchanger where the cold water valve is open in a countercurrent flow arrangement to cool the milk and essentially warm the cool water passing therethrough.
The transition from pasteurization to cooling is done in a batch process as well where the fluid is circulated through the heat exchanger contained in the lower region to bring it to the calf feeding temperature. The PLC controller is fully adjustable by the user for the heating temperature and the cooling temperature time durations. In one preferred form, once the pasteurizing is done and the temperature is brought to the appropriate level for calf feeding, the machine unit subset shuts off and is done the batch process.